Have been suffering from recurring nightmare occasioned, (probably) by watching too much Big Brother, travelling too much by train and spending too long on planet paranoia.

Unlike most nightmares, where you wake up and realise they were a dream, this one is so entwined with reality that it's hard to know exactly which bits I have dreamed and which are real.

So the nightmare scenario is - I have to travel by train from Brighton to London every day. I tend to go in roughly the same carriage and, although I don't know my fellow commuters personally, I know them all by sight and to exchange the odd word with.

I feel as if they're allies and if I see them out in the real world I'll probably say hello or even chat to them. We have a shared sense of commuter solidarity.

But, the train is overcrowded and not everyone will get a seat. So, every now and then someone is ejected at a station along the route. I discover that, by trying to encourage people to sit in certain places, I can manipulate who is ejected.

So, I give up my seat near the door to businessman from Burgess Hill, who is thrown out at Three Bridges. I offer the fresh-air freak from Preston Park a seat near the window. She is taken off at Wivelsfield. Then I go to buy colleague coffee and leave for the buffet just as he is selected for eviction at Gatwick Airport. Finally, I have the carriage to myself.

Initially fellow travellers seem to like me. After all, I'm always giving up my seat and doing tea runs. But, after a while, they begin to suspect I'm up to something.

Blond athletic man from Hassocks, who I've always regarded as an ally, confronts me and accuses me of tactical seating manoeuvres. I deny it but the others join in. I still deny it.

Then the guard enters the carriage. He tells me that Connex has installed CCTV on board all trains in order to discourage vandalism. He has video evidence of my duplicity, which he shows to other commuters. They shake their heads and look at me with a mixture of pity and disgust. I am forced to leave the train at Haywards Heath and, as I do so, blond athletic man from Hassocks refuses to make eye contact and says disappointedly: "I always thought you were my friend..."

Then, the alarm goes off and I realise it was all a dream. Apart from the having to go to work every day by train, which is why the alarm went off, reminding me to get up, get dressed and make way to station so I can get a seat in overcrowded carriage and try to make sure there is room for blond athletic man from Hassocks.

I tell friend Mark about dream who does little to reassure me, by telling me it is based entirely on reality as, a) the trains are overcrowded, b) I do try to manipulate the seating, to ensure I always get a seat near the window, travelling forward and as near as possible to blond athletic man from Hassocks, c) it's blatantly obvious to everyone else in carriage that I am guilty of b and d) he thinks Connex are planning to introduce CCTV. So, it won't be long before they have video evidence of a,b and c. Mark goes to get us both a coffee, as train nears Hassocks. Blond athletic man gets on, while he is still in buffet and asks if vacant seat is free.

"Afraid not." I tell him. "My friend's sitting there. He's just gone to the buffet."

Hassocks shakes his head, disappointedly, and says: "I always thought you were my friend."